kselftest/arm64: Validate that changing one VL type does not affect another

On a system with both SVE and SME when we change one of the VLs this should
not result in a change in the other VL. Add a check that this is in fact
the case to vec-syscfg.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230720-arm64-fix-sve-sme-vl-change-v2-3-8eea06b82d57@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

Author: broonie

tools/testing/selftests/arm64/fp/vec-syscfg.c

@@ -554,7 +554,8 @@ static void prctl_set_onexec(struct vec_data *data)
 /* For each VQ verify that setting via prctl() does the right thing */
 static void prctl_set_all_vqs(struct vec_data *data)
 {
-	int ret, vq, vl, new_vl;
+	int ret, vq, vl, new_vl, i;
+	int orig_vls[ARRAY_SIZE(vec_data)];
 	int errors = 0;
 
 	if (!data->min_vl || !data->max_vl) {
@@ -563,6 +564,9 @@ static void prctl_set_all_vqs(struct vec_data *data)
 		return;
 	}
 
+	for (i = 0; i < ARRAY_SIZE(vec_data); i++)
+		orig_vls[i] = vec_data[i].rdvl();
+
 	for (vq = SVE_VQ_MIN; vq <= SVE_VQ_MAX; vq++) {
 		vl = sve_vl_from_vq(vq);
 
@@ -585,6 +589,22 @@ static void prctl_set_all_vqs(struct vec_data *data)
 			errors++;
 		}
 
+		/* Did any other VLs change? */
+		for (i = 0; i < ARRAY_SIZE(vec_data); i++) {
+			if (&vec_data[i] == data)
+				continue;
+
+			if (!(getauxval(vec_data[i].hwcap_type) & vec_data[i].hwcap))
+				continue;
+
+			if (vec_data[i].rdvl() != orig_vls[i]) {
+				ksft_print_msg("%s VL changed from %d to %d\n",
+					       vec_data[i].name, orig_vls[i],
+					       vec_data[i].rdvl());
+				errors++;
+			}
+		}
+
 		/* Was that the VL we asked for? */
 		if (new_vl == vl)
 			continue;